Fighting between Israeli forces and Hamas militants has been reported from several areas in Gaza after Israel launched a ground offensive into the Palestinian territory Saturday evening. Israel says 30 of its troops have been wounded, two seriously and it claims to have killed or wounded dozens of Hamas militants. Gaza officials put the Palestinian death toll from the week-long Israeli operations at around 500.

Israeli soldiers crossed the border under cover of darkness Saturday night and fanned out across areas of the northern Gaza Strip.

Troops and tanks are reported to have moved into positions, including around Gaza City. Tanks are reported dug in at some former Israeli settlements in Gaza and the military action is reported to have effectively cut the Gaza Strip in two between north and south.

Israel used its infantry, tanks, artillery, war planes and navy to hit more than 40 targets just overnight.

Speaking before an Israeli cabinet meeting Sunday, Prime Minister Ehud Olmert said the decision to launch the ground offensive was made Friday.

Mr. Olmert said the decision was not made lightly and only after months of waiting and after hopes for calm were dashed.

Mr. Olmert vowed that the government did everything before deciding on this operation. "It was unavoidable," he said.

Israel has said all along it had no choice but to launch military action after talks with Hamas on extending a cease-fire broke down in December and militants stepped up rocket fire against southern Israel.

Israel initially launched air strikes just over a week ago, pounding targets it said were linked to Hamas and its infrastructure in Gaza.

But, Hamas has remained defiant, warning that it would turn Gaza into a graveyard for the Israelis.

Casualties are reported on both sides, including Israeli soldiers, Hamas fighters and Palestinian civilians, including children.

According to tallies by medical officials in Gaza the Palestinian death toll from Israeli military operations is now around 500.